The 4th Circuit upheld that ruling and found that a forensic search of electronic devices requires “individualized suspicion” of wrongdoing. The court said agents had that suspicion because Kolsuz had made two previous attempts to smuggle weapons parts out of the U.S.

The Fourth Amendment requires law enforcement to obtain warrants based on probable cause. But courts have made an exception for searches at airports and U.S. ports of entry, finding that the government can conduct warrantless border searches to protect national security, prevent transnational crime and enforce immigration and customs laws.

The American Civil Liberties had urged the 4th Circuit to find that the government should be required to obtain a warrant or at least a determination of probable cause that evidence of a crime is contained on electronic devices before agents can search them at airports.

The 4th Circuit said it did not have to reach the question of whether probable cause or a warrant is required. Reasonable suspicion is a lower legal standard.

Claire Gastanaga, the executive director of the ACLU of Virginia, said the group is pleased that the appeals court “recognized correctly that border agents can’t conduct invasive searches on a traveler’s cell phone or other electronic devices just because the person is crossing the border.”

Last year, the ACLU filed a federal lawsuit claiming warrantless border searches are unconstitutional because of the vast amount of private personal and business information stored on electronic devices.